Demons Against Devils
by Sgt. Cheerleader
Summary: Just when the Renkai Tentai thought they were done in the tournament scene, Koenma's next case thrusts them directly into a new one - The King of Iron Fist Tournament.


_Tekken and YuYu Hakusho are two of my favorite franchises in any medium period. They both have kickass characters and storylines, so I thought, why not combine the best of both worlds and do a unstoppable force vs immovable object kinda thing?_

 _I don't own any of these characters; Tekken and their characters belong to Bandai Namco, and YuYu Hakusho belongs to Yoshihiro Togashi._

 _Without further ado, here's Demons Against Devils!_

 _ **GET READY FOR THE NEXT BATTLE!**_

* * *

"Heihachi Mishima? Who the hell is that?" Yusuke asked, sitting across from his boss. The foursome of the Reikai Tentai all stared at Koenma, who had an urgent new assignment for them that required all of their skills. Hiei protested of course, but Koenma assured him it would be worth his while.

"He's a giant pain in the neck as far as I'm concerned." Koenma replied. The prince regarded the four boys with wringing hands and a concerned look. Despite his child like form, his expression conveyed the true gravity of the situation. "I've been saving this case until I was sure you could at least have a fighting chance of handling it."

Yusuke was about to open his mouth and give Koenma shit for doubting them, but Hiei beat him to it. "Tch. Don't you think we've earned a little credit, Koenma? We've saved Living World countless times from annihilation, and you've seen our abilities up close AND in person. Yet you're still foolish enough to doubt us?"

"Shorty's right!" Kuwabara announced, his fist meeting his open palm. "Ever since I finished up with college and started training with Kurama, I've been ITCHING to get back into a good old fashioned brawl!"

"I'm afraid it's a little bit more serious than that, Kuwabara." Koenma turned to look at the fire demon. "To answer your question, Hiei, I don't doubt you or the others in the least, but these aren't your everyday B-class troublemakers you're going to be dealing with."

"Okaayyyy, but what could be worse than B-class losers anyway? The three of us demons happen to be S-class in case you forgot, and Kuwabara's no slouch either. We could whoop any bunch of scrubs that causes trouble." Yusuke reminded his boss. Koenma them shook his head.

"They're not demons, Yusuke. They're far worse."

"Which is?" The spirit Detective raised an eyebrow, his interest piqued. Hiei and Kuwabara also looked curious, while Kurama remained silent.

The Prince of Spirit World narrowed his eyes.

"They're **Devils**."

Hiei and Kurama gasped, their eyes wide. "That...that's impossible." Hiei exclaimed.

Yusuke and Kuwabara, however, were unimpressed. "Uh, correct me if I'm wrong, but aren't demons and Devils the exact same thing?" Kuwabara deadpanned, matching Yusuke's bored glare.

"I'm afraid not, Kuwabara." Kurama declared, his expression more serious than usual. "Devils are legendary creatures in Demon World. They're said to be obsessed with creating chaos and suffering, and to possess a malice so brutal and violent that even S-class demons know to watch themselves around them. The popular narrative is that they were born directly from the fires of Hell, and wreaked havoc on every plane of Demon World they happened to come across. However, by some method, they became extinct. Some think they were trapped to a divine prison by a more benevolent force. Others say they simply went to sleep, waiting for their next opportunity to bring chaos. No one knows how or why, or even if they existed at all."

"They're simply fairy tales. A method just to get unruly children to behave." Hiei announced. "Koenma, are you sure that these aren't just highly skilled demons that got through the Kakai Barrier, and managed to not be caught?"

"There are several photographs from my reapers in the file that disprove that theory, but I'm sure a video would convince you best." He clicked his remote, and the boys turned around to watch the monitor, which displayed two men fighting on top of a tall building's helicopter pad.

"The problem not only lies with Heihachi, but with these two as well. They happen to be Heihachi's son and grandson."

The man with a large scar on his chest appeared to have the upper hand, and it showed when he dodged a haymaker punch from the tattooed one and landed a harsh punch to the other's stomach that caused him to crumble to his knees. A smirk graced his features as he relished in the other one's pain.

"The one standing is known as Kazuya Mishima. On the surface level, he appears to be a human businessman, in charge of G Corporation, a company that specializes in genetic technology. But we know that he's actually a Devil. He's responsible for a lot of human misfortune; ordering raids simply for being career opponents, intimidating everyone around him with fear and violence, and even performing experiments on wild animals for combat reasons."

"Ugh, I already don't like this asshole. Guys named Kazuya and I don't get along very well," Yusuke said, thinking back to his experience in the caverns with the violent Sensui personality.

"The other one is named Jin Kazama. At one point, he was in charge of the Mishima Zaibatsu, a private military conglomerate that is now currently governed by Heihachi. We know that he's a Devil, too, possibly more dangerous than Kazuya."

Kazuya walked slowly over to his son, stopping just above him. Just as Jin slowly looked up at him, Kazuya's gloved hand grabbed Jin's neck in a chokehold and lifted him off the ground, the younger one's feet dangling in the air. Jin frantically grabbed at his father's arm, but this only seemed to increase Kazuya's amusement.

"This Kazama one doesn't appear to be much of a Devil." Hiei muttered. "Just keep watching," Koenma barked, a little frustrated by the lack of patience.

Kazuya's smirk suddenly disappeared, and he barely had any time to react when a bright red light started to emit from Jin's forehead, and quickly manifested into a laser beam that landed directly into Kazuya's chest, knocking him a far distance back. Although he was no longer being choked, Jin still continued to writhe in pain. Horns began to poke out of his scalp, two brown, jagged spikes. His body slowly became decorated with sharp, tribal tattoos, most prominently a design wrapped around the newly grown red eye on his forehead.

"Hey Hiei," Yusuke spoke up, "that kinda looks like your Jagan eye. Can those only be surgically attached or can they be natural, too?"

"I certainly hope not. When I had mine implanted, it set me back to where I had to re-learn all my power. If one were to master the Jagan Eye on their own, there's no telling how powerful it could be." The fire demon replied.

"Geez, imagine if Hiei could shoot lasers out of his creepy eyeball." Kuwabara whispered to himself, shuddering at the thought.

Jet black wings began to grow out of Jin's back, and his gauntlets were shredded open by the appearance of talon-like claws. He stood up after the wings finished growing to their full span, the transformation complete. Scarlet red electric slugs started to manifest all over him, and he growled, his voice gaining an echo. He finally stood up straight and walked slowly toward Kazuya, who was getting up himself. Kazuya appeared to be more frustrated than anything, and stood rigid. He bent over and back up again, throwing his arms up with a shout. Almost instantly, his skin transformed from its normal tone to dark purple scales. Horns manifested out of his head, and wings instantly came out of his back. A louvered tail danced back and forth as he readied himself. Jin broke into a short run and took flight, and smashed right into Kazuya, pushing him almost to the edge of the building. Both beasts grappled for control, their hands clasped together. Jin managed to force Kazuya to one knee, and quickly let go of one hand to throw a punch aimed at his face. Kazuya's reflexes were quick however, and easily caught Jin's punch. Blue lightning manifested around the elder Devil's arms, and he twisted Jin's arms downward to meet Jin's forehead with a massive headbutt. Jin stumbled backwards, and before he could recover, Kazuya spun around and crashed his right heel directly into Jin's face, sending him sprawling.

Out of the corner of his eye, Yusuke noticed Kuwabara's worried glare. He stared at the screen with eyes wide open, visible beads of sweat running down his cheeks.

"You okay there buddy?" Yusuke asked. Kuwabara simply gaped in response. "You mean you don't feel that? Their energy… I can feel how much they hate each other, how much they want the other to suffer… it's making me feel sick!" Indeed, Kuwabara's skin had turned a light shade of green.

Jin's wings carried him up off the ground, landing solid on his feet. He wiped the blood off his face with his arm, growling as Kazuya laughed.

"It's hopeless. That Devil form of yours can't help you. Unlike you, I had the fortitude to welcome my ascension with open arms. I am much stronger than you ever will be." Kazuya crossed his arms, regarding his son with a sneer. "Soon, your Devil Gene will be mine. After that, I will end your pathetic life, and then my father's. You can both burn in Hell as I reign over the world." Again, he laughed, disregarding Jin's downright evil stare. If looks could kill, Kazuya would have been eviscerated long ago.

"I'll never stop. I won't let anymore innocent people suffer. The Devil must be exorcised from the Earth. This ends right here, right now!" Jin shouted in defiance.

"On that, we agree. I'm done playing around. It's time for you to learn your place, BOY."

With a cry, Jin flew full speed at his father, who followed suite. Closer and closer until finally their fists clashed, blue and red electricity mixing on each of their bodies. The clash emitted a slow shockwave, taking out of most of the city's surrounding power and whipping wind around like crazy.

Yusuke blinked as Koenma's TV was showing static instead of the climactic finish to the fight.

"Unfortunately, their sheer power fried our vision system. That's all the footage we have so far. More info can be found in the file."

The Reikai Tentai turned around in his seat to look at Koenma. "Where the Hell is Grandpa in all of this, then? He has to know that this is happening. He's not trying to make em fight to see who's stronger or whatever, is he?" Kuwabara questioned.

"Heihachi doesn't seem to care about what Kazuya or Jin are doing right now. We've received word that he has been doing some experiments of his own. He managed to obtain the blood samples of a creature known as Ogre, an apparition with the title of God of Fighting. Jin had defeated it some time ago, but when he did, Heihachi personally murdered Jin, leaving him to die as he took Ogre's body to an unknown location. He was last seen in Mexico, but we have reason to believe he's back in Japan. Jin's not dead as you can plainly see; the Devil inside of him kept him alive and revived him long after Heihachi had gone."

"I assume this Heihachi is planning some sort of sinister scheme with the body of this Ogre creature?" Kurama asked.

"As usual Kurama, you're dead on the money. Based on our information gathered, Heihachi is attempting to manufacture apparitions of his own design to create his own personal demon army, which is VERY bad news. As you boys witnessed, Kazuya's desire is clear: he wants to absorb the Devil power from his own son to completely transcend his humanity. If that happens, there's no telling if even all of us and our friends combined could stop him. And that's not accounting for Jin either; his Devil form seems to be even more violent and aggressive than his father's. It goes without saying we need to put a stop to this now."

"So what are we waiting for? Let's get back to Living World and kick some ass!" Yusuke said, a cocky grin taking up most of his face.

"Not so fast, Yusuke. While we know the truth about this family, both Heihachi and Kazuya have the benefit of good public reputation working against only that, but Jin has been reported missing, with Living World's United Nations tracking him down for his own crimes. As much as I know you're tempted, you can't just waltz in to wherever they are and blow them away with your Spirit Gun."

"You got any better ideas, binky breath? We can't just invite them for a picnic."

"I'm getting to that, smart ass. Heihachi's downfall seems to be his immense ego; every now and then, he holds what he calls the King of Iron Fist Tournament, a gathering of the world's best martial artists to fight for the ultimate prize; the Mishima Zaibatsu itself. Of course, no one other than Heihachi himself wins; he is an impressive martial artist in his own right, and he seems to hold these tournaments just to have the smug satisfaction of crushing the finalists himself. You're in luck gentlemen, because The King of Iron Fist Tournament was just announced once again - and you'll be entering as contestants."

"Oh great. I don't know about the rest of you guys, but I'm getting kinda tired of all these tournaments." Yusuke sneered.

"It seems that this King of Iron Fist Tournament would explain where Heihachi has gone, which gives us a starting point to find him."

"Correct, Kurama. Whether any of you like it or not, it's the perfect opportunity to not draw attention to yourselves. Gentlemen, your mission is clear; stop these men, or Living World is done for."

"As much as I hate doing your bidding, Koenma, I must say that the opportunity to take down a Devil is quite endearing." The Jagan Eye began to glow underneath its headband cover as Hiei smirked. "Mukuro will have no choice but to regard me as an equal, or better yet, her superior. Imagine what I could accomplish if I had both her and her armies under my command."

"Indeed. If I were to subdue a Devil, no one would think to even go anywhere near my human mother." Kurama said, thinking out loud.

"I don't care who it is or if they're some powerful Devil or whatever, it's gonna feel good cracking some skulls again!" Kuwabara shouted.

"You guys already know I don't back down from a challenge." Yusuke said, a gleam in his eye.

"You see, gentlemen? I told you it would be worth your while. Yo, Botan!"

The blue haired reaper burst in through the door, her smile as cheery as ever. "You called for your favorite servant, sir?"

"The team has another case to take care of. Go ahead and escort them to Living World."

The bluenette saluted, happy to help. "Understood sir!" The boys stood up from their seats and gathered around her as she dug around in her kimono. She made a little sound of victory as she pulled out a small little device, nothing more than a remote with a big red button and an antenna. Giving it a click, a bright blue portal shot out of the antenna, right next to Koenma's desk.

"Well boys, it's ready when you are!"

"This might actually be pretty fun." Yusuke said, the first to walk in the portal. The others followed suit.

"Goodbye, sir! Don't forget to send us some goodies!" The bluenette waved goodbye as she stepped in the shimmering blue, and it dissipated behind her.

Koenma sighed, closing his eyes shaking his head. "I hope I haven't made a grave mistake." He quickly cleared his throat. "Yo, Jorge."

The doors slammed open again as the big blue ogre sauntered in, panting heavily as if he had been running for hours. He finally arrived next to Koenma, his hands on his knees, trying to recover his breath. "Koenma sir," he managed to say between sharp breaths, "What can I do for you?"

"When you're done being a drama queen, you can fetch me some sushi and rice cakes. Yusuke and the others are on another mission and I want some popcorn for my front row seat to the show."

Jorge ignored the order given to him and got visibly excited at the news of the Reikai Tentai. "Really? Man that's awesome! I can't wait to see Yusuke and the others kick major butt again! I never thought I'd see the day!"

He would have geeked out a lot more if Koenma hadn't given him a sharp rap directly on the head. "LESS TALKING AND MORE FOOD FETCHING YOU BIG USELESS BUFFOON!"

Despite the pain, Jorge carried on with his task. "Right away sir…" he uttered in a defeat tone.


End file.
